扩展的 CONNECT 协议

RFC 8441 定义了 HTTP/2 的“扩展连接协议”扩展，可用于引导使用 Http2Stream 使用 CONNECT 方法作为其他通信协议（例如 WebSockets）的隧道。

扩展连接协议的使用由 HTTP/2 服务器通过使用 enableConnectProtocol 设置启用：

const http2 = require('http2');
const settings = { enableConnectProtocol: true };
const server = http2.createServer({ settings });

一旦客户端从服务器收到指示可以使用扩展 CONNECT 的 SETTINGS 帧，它可能会发送使用 ':protocol' HTTP/2 伪标头的 CONNECT 请求：

const http2 = require('http2');
const client = http2.connect('http://localhost:8080');
client.on('remoteSettings', (settings) => {
  if (settings.enableConnectProtocol) {
    const req = client.request({ ':method': 'CONNECT', ':protocol': 'foo' });
    // ...
  }
});

RFC 8441 defines an "Extended CONNECT Protocol" extension to HTTP/2 that may be used to bootstrap the use of an Http2Stream using the CONNECT method as a tunnel for other communication protocols (such as WebSockets).

The use of the Extended CONNECT Protocol is enabled by HTTP/2 servers by using the enableConnectProtocol setting:

const http2 = require('http2');
const settings = { enableConnectProtocol: true };
const server = http2.createServer({ settings });

Once the client receives the SETTINGS frame from the server indicating that the extended CONNECT may be used, it may send CONNECT requests that use the ':protocol' HTTP/2 pseudo-header:

const http2 = require('http2');
const client = http2.connect('http://localhost:8080');
client.on('remoteSettings', (settings) => {
  if (settings.enableConnectProtocol) {
    const req = client.request({ ':method': 'CONNECT', ':protocol': 'foo' });
    // ...
  }
});